1. Field of the Invention
The present invention relates to a device for simultaneously tamping and leveling concrete and similar materials, and more particularly relates to a device of the described type which includes a work-engaging surface of substantial length to facilitate use of the device upon a segment of material having a relatively large surface area.
2. Description of the Prior Art
It is generally recognized and appreciated that the strength and appearance of materials such as concrete may be enhanced by compacting the plastic mass by tamping and vibrating the material. A variety of mechanical devices have been designed for performing these operations and for reducing the amount of manual labor required. It is of course desirable that these devices perform properly and efficiently, while being inexpensive and easy to operate. In addition to working the concrete or similar material to increase the density and appearance, it is also desirable that these devices assist in the leveling and planing of the material. A typical device of this type customarily inncludes a member having a work-engaging surface, a motor superposed upon the member for rotating or vibrating the same, and a handle to facilitate control over the device. The devices of the prior art, however, have generally been poorly suited to certain applications, such as leveling and tamping concrete and the like which has a substantial surface area.
The concept of applying a vibratory motion to the work-engaging surface is known in the art. In U.S. Pat. No. 1,657,727, issued to Stubbs on Jan. 31, 1928, there is disclosed a device for compacting concrete which includes a generally rectangular bottom surface and means for vibrating the surface. The surface is vibrated by a series of reciprocating plungers which are mounted directly above the surface member. Although the Stubbs' device is suitable for its intended purposes, the design of the device is not practically adaptable to use with a work-engaging surface member of substantial length. If the work-engaging member were expanded in dimensions over that indicated in the patent, the number of reciprocating plungers would be sufficiently great that the device would be unmanageably heavy and bulky and would also be expensive. Similar comments are appropriate with respect to the devices disclosed in U.S. Pat. Nos. 3,386,353, issued to Wells on June 4, 1968, and 2,209,656, issued to Mall on July 30, 1940. The devices disclosed in each of these patents includes a relatively small work-engaging surface member with a relatively large motor mounted thereupon. The mere expanding of the size of the work-engaging member would result in a device which would be considerably bulky and difficult to manipulate.
The difficulties which arise with respect to the working of a large area of concrete or similar material are suggested in U.S. Pat. No. 2,048,071, issued to Jacobson on July 21, 1936. The patent discloses a device which has a substantial length dimension, and which may be vibrated to tamp and level the material upon which it is acting. The Jacobson device is particularly intended for finishing concrete pavements and the like and includes a roller of considerable length for engaging the concrete. The Jacobson device, however, employs a complicated mechanism for suspending and vibrating the roller, and as a result entails considerable expense and bulk. It would certainly be preferable to provide a tamping and leveling device which could operate over a large surface area but which would not entail such complexities of design and function.